I made a 22 sq ft rabbit (or guinea pig) cage for less than $90, and here's how

Obligatory finished product

This is after I set everything up in my apartment

The inspiration

This cage is from www.guineapigcagesstore.com and is about $150. It's actually extremely difficult to find small animal cages that are of decent size and are affordable, so I used this idea as my own guide to making one myself.

The design

These are the sizes of the trays I needed because I wanted the cage to have a bottom tray that is 5 panels long (14 x 14 in each) and 2 panels wide, with the top loft being 3 panels long and 2 wide. The back of both trays are taller in an attempt to keep the shavings from getting behind the cage.

The materials

Note: price of coroplast is for a 4 x 8 ft sheet
If you just do the bare minimum, the shelving unit & coroplast, & 1 door (like I did), this cage should cost around $89 (the shelving unit was $55 when I bought it, I see that it is now $66).
I added in the extra connectors set because the organizer from amazon doesn't come with enough to make this rabbit cage (mostly because it's designed to be a shelving unit, not a rabbit cage). I did not purchase this set because I don't mind using zip ties for the few joints that didn't have connectors.
Costs not factored in:
shipping
X-acto knife
sharpie
tape measure
straight edge
zip ties
helpful dad
hot glue gun & hot glue
rabbit

Basic wire frame laid over coroplast

Just making sure measurements were accurate before any permanent cuts were made

My dad cutting the sheet of coroplast

At this point we moved inside because it was 33 F in our garage and we are but thin-blooded Texans

Example of a partial cut

I had to make these on the outside of the trays so that I could fold & glue the plastic